There is a mournful tone to Brian Topp’s post-mortem on the last B.C. election, as one might expect: the NDP, whose campaign he directed, went down to defeat, though it led in every poll until the end. And yet it is not for himself or his party he weeps. It is for us.

Through its 42 carefully leaked pages, the document attempts a degree of self-criticism. Various strategic errors are confessed. There were opportunities missed, warning signs that should have been heeded. But mostly it is a lament for the state of modern politics. What has this world come to, it seems to ask, that good people like us could be defeated?

The Liberals were re-elected, he argues, because they played dirty, while the NDP took the high road. “We undertook a principled, admirable and well-intentioned attempt to conduct a positive campaign,” he writes, “in the face of an opponent playing by the right-wing populist playbook.” While the NDP made a point of avoiding personal attacks on Premier Christy Clark, the Liberals went after Adrian Dix with lusty abandon.

There were many reasons, but one that Topp pinpoints is Dix’s determination to run a clean, professional, no-insult campaign. There were to be no personal attacks on Premier Christie Clark, despite plenty of Liberal party gaffes to provide material. Dix didn’t want hokey old-style events showing the leader surrounded by cheering enthusiasts or beaming voters waving banners or placards. He wanted a principled, positive campaign in which the party laid out its vision for a new style of government to replace the dirty, cynical, vote-buying practices of the incumbents.

He got creamed.

“A more aggressive, bloody-minded campaign than the one we conducted would have nonetheless acted on the traditional political principle that the best time to kick your opponent is when they are down,” wrote Topp, who is no bright-eyed rookie. He has years of experience in NDP war rooms, was a key adviser during Jack Layton’s breakthrough 2011 federal campaign, and was a candidate to succeed Layton after his death.

“Parties who ask for mandates to ’change politics’ risk sounding like they are talking about themselves instead of about the electorate,” says Topp.

Enter Justin Trudeau. The Liberal leader has based his appeal thus far on his image as a cheerful, optimistic, energetic young newcomer who wants to chuck out the old ways of doing business in Ottawa and introduce an open, engaging, personable approach. He’s done very well so far, just as Mr. Dix did in the months before B.C.’s election was called. But, as Mr. Topp discovered, generalized impressions before an election are one thing. It’s wholly different when the writ is dropped and the mud starts flying.

Failing to attack Ms. Clark let her escape blame for past mistakes, he writes. While Dix was being pummeled in nasty attacks of questionable honesty, the NDP failed to fire back. Mr. Dix thought voters would focus on the specifics of his policies, as they always claim to prefer. In reality it’s impressions that stick, and voters got the impression Mr. Dix was remote and long-winded, while Ms. Clark was cheerful and friendly. In preparing for debates, Topp wrote, it’s better to stock up on “zingers” to fire at opponents rather than get “mired” in policy.

On that front Mr. Trudeau is safe, as he’s revealed few policies and says he has no plans to do so until the 2015 election. He is far more personable than Mr. Dix, and there’s little danger the Liberals, having lost two previous leaders to Tory attack ads, will risk losing another without hitting back. But there’s an inherent risk in that: the more they match the Tories in aiming low, the harder it will be to maintain the notion of Mr. Trudeau as a new style of politician.

Mr. Topp notes that Dix failed to convince voters the NDP had sound alternatives to the Liberals. They also made the fatal mistake of assuming voters were as tired of the government as polls suggested. Mr. Harper is a skilled, veteran leader who has been repeatedly underestimated by opponents to their detriment. It’s safe to assume he’ll throw everything he has at Mr. Trudeau, and then some. Voters may not have warmed to him, but he’s won three previous elections despite that fact.

He’s not unbeatable, but the Liberals might want to take a lesson from Mr. Topp, and Mr. Dix, in sorting out how to do it. They learned the hard way that voters can’t be taken at their word: they may claim they want a clean campaign dominated by serious debate, but they don’t mean it. In the end the old methods work better, which is why they’re still used. The high road is fine for sightseeing, but it’s not necessarily the route to victory.